Arne Brennan, co-designer of the 6.5 Grendel and ammunition wizard continues to invent new cartridge options for the AR-15 rifle. Last year, Raptor Shooting Systems released the .45 Raptor, a round based on the .308 Winchester that advertises superior performance to other big bore AR-15 rounds like the .50 Beowulf, .450 Bushmaster, and .458 SOCOM. Now, Brennan’s company has announced two new smallbore rifle rounds for the AR-15, the 7mm Raptor (stylized 7 RAPTOR) and the .257 Raptor (257 RAPTOR). From the 7 RAPTOR website:

The 7 RAPTOR is a .284 caliber / 7mm AR-15 cartridge designed for target shooting and  medium game hunting out to 300 yards.

The cartridge and chamber design are optimized for AR-15 magazine loading at a 2.26 inch overall length using AR-15 standard 5.56 bolt and magazines.

The 7 Raptor is ideally suited to bullets between 100 grains and 130 grains in weight.  However, the 7mm Raptor can handle 7mm bullets up to 168 grains.

…

So with the 6.5 Grendel project behind me, the challenge became could I develop another cartridge for target shooting and medium game hunting for use out to 300 yards and keep it cost effective and simple.

To achieve this goal, the design criteria of the cartridge specified that it possess many of the same key dimensions as the 223 Remington to allow use of the standard 5.56 bolt and magazines.    As well,  being based on the 223 Remington would give the end user an abundant source of economical brass to work with.   Finally, the design criteria required that the cartridge maintain close to a “one caliber” neck length to support the bearing surface of the bullet.   With the parameters of the parent case decided, the next step in the process became the decision on caliber.

In considering caliber options,  7mm offered improved external ballistics over 30 caliber when comparing equal bullet weights.  In comparing 7mm to 6.5mm, 7mm bullets are shorter, when comparing bullets of equal weight, preserving powder capacity in a small capacity case constrained to 2.26″ OAL.  In addition, it was found that a 7mm cartridge would not interfere with the forward ribs of standard 5.56 AR15 magazines allowing loading to 2.26 inches without restriction.

In creating the final design, the cartridge is able to be formed from either 223 Remington or 222 Remington brass with a full “one caliber” neck length for proper bullet bearing surface support.   Finally, the case capacity and caliber combination  proved ideal for widely available powders such as AA5744, AA1680, AA2200, Reloader 7, H4198 and Vihtvouri N120.

While others have attempted wildcats that amount to a shortened 7 TCU, the 7 RAPTOR is not a shortened 7 TCU.    The 7 TCU is created by necking up the 223 Remington and fireforming the case to create a 40 degree shoulder and remove the body taper.   Shortened versions are created by machining the base of TCU dies and by holding short a standard 7 TCU reamer.   In contrast, the 7 RAPTOR retains the body taper of the 222 Remington and forms the shoulder angle at the same time as expanding the neck from .224 to .284 with the full length resizing die and tapered expander.  Since the 7 RAPTOR is designed for a semi-automatic rifle, clearances were introduced to enhance feeding and extraction compared to the 7 TCU which was designed for a single shot handgun or bolt action rifle.  Taken further, the throat design of the 7 RAPTOR was created for a 2.26″ overall cartridge length using the ideal bullets in the 100 to 130 weight range.   In comparion, the throat design of the 7 TCU was designed for loading bullets “long” to overall lengths as great as 2.5 inches and this would create excessive free-bore even when shortening the cartridge from the back end.

The 7 RAPTOR website lists these performance figures for the cartridge, from a 24″ barreled AR-15:

May 4, 2015 Field Test Report

Speer 110 Grain TNT: 2710 fps obtained with both AA1680 and AA5744

Speer 130 Grain BTSP: 2435 fps using AA1680

Nosler 150 Grain Accubond Long Range: 2075 fps using AA1680

All tests were performed at cartridge OAL of 2.26 inches using Winchester 223 Remington brass that had been formed and trimmed to 7 RAPTOR.

The 7 RAPTOR differs from the recently released Kramer Defense 6.8×45 UCC by using .284″ bullets instead of .277″ bullets, and having a 5mm shorter case with correspondingly reduced powder capacity and increased space for a more slender projectile ogive.  Unlike the 6.8×45 UCC, the 7 RAPTOR is intended as a dedicated 300 yard medium game hunting cartridge, for which it is broadly suitable with appropriate-length barrels.

The 257 RAPTOR is intended as a medium game and varminting round. Interestingly, a similar relationship exists between the 257 RAPTOR and the .25-45 Sharps. The Sharps round, like the 6.8×45 UCC, chases high muzzle velocity over all over characteristics, within the confines of the .223 case. In contrast, the 257 RAPTOR accepts a reduced case capacity through a shortened .223 or .222 Remington case, in exchange for allowing slender, higher-BC bullets that retain energy well. As the 257 RAPTOR website points out, the .25-45 Sharps doesn’t get much benefit from its longer case, anyway, as the seating depth of the bullet eats up much of the earned case capacity.

UPDATE: Arne Brennan wrote to us …

[The 7 Raptor is ] in development along with the 257 Raptor and not sure what, if any, product will ever be released. May just let people buy reamers from pacific tool and do it themselves.